Contactless Extraction of Implied I-V Curves of Individual Solar Cells in Fully Assembled Modules Using Photoluminescence

Degradation of photovoltaic modules is one of the key aspects determining the power output and thus the financial viability of solar power plants. Furthermore, it is known that individual cells in PV modules degrade at different rates. The specific cell's degradation rate depends on many factors and generally exhibits an injection dependent nature. Thus, a current-voltage measurement of a specific cell can provide valuable information to determine the extent of degradation and identify the prevalent degradation mechanism. Although various inspection methods can be used to identify degraded cells, so far none of them provide the ability to extract the current-voltage characteristics of an underperforming cell by a contactless and non-destructive method. In this study, we present a photoluminescence based, contactless, fast, simple, and highly sensitive method to obtain the implied current-voltage curve of individual cells already embedded in solar modules. The method is validated by comparisons with Suns-V
_oc
measurements.